the question has been raised whether Bronze or iron naval cannon was preferred at the end of the eighteenth century, and the topic is interesting enough that a discussion , rather than a tit for tat exchange , is called for.

Bronze casting was a 'speciality', and bronze is an expensive metal. Cost considerations and speed of arming often dictated iron.

Bronze guns were lighter, since bronze can be made with a 'thinner' wall, although bronze is 'denser'. the Napoleon field piece was usually bronze, since field cannon have to be mobile. boat howitzers were usually bronze for the same reason.

Iron ore selection is crucial in casting cannon that will not fragment. the best cannon ore came form Sweden and could be hard to obtain in wartime..

Conversely, Britain had copious supplies of copper, and some tin, although tin is the limiting ore.

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The trout who swims against the current gets the most oxygen..

The decision was "what is available', and what the wartime budget allows. first dibs for bronze in rearming went to field armies and boat crews.

USS Hetzel, a converted Coastal Survey ship armed with 1 IX-inch Dahlgren and 1 80-pounder Dahlgren rifle was engaged in the bombardment of Roanoke Island in support amphibious landings, when the following entry was made in her log for February 7, 1862: “At 5:15, rifled 80-pounder aft, loaded with 6 pounds powder and solid Dahlgren shot, 80 pounds, burst in the act of firing into four principal pieces. The gun forward of the trunnions fell on deck. One third of the breech passed over the mastheads and fell clear of the ship on the starboard bow. One struck on port quarter. And the fourth piece, weighing about 1,000 pounds, driving through the deck and magazine, bringing up on the keelson, set fire to the ship. Fire promptly extinguished.” (Ripley 1984, p. 106)

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The trout who swims against the current gets the most oxygen..

the shattering problem was solved by John Dahlgren , by designing heavier breech castings, and by 'rodman casting, which reverted to the ancient interior of an interior casting tube. the tube was used to control the rate of cooling, so the metal cooled form the inside out, compressing the inner gun tube.http://ca.yhs4.search.yahoo.com/yhs/...ansfer&iscqry=

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The trout who swims against the current gets the most oxygen..

By the era of the Revolutionary/Napoleonic Wars the majority of naval cannon were made of iron simply because it was far cheaper, and with the huge number of cannon needed quantity vs. quality became the main issue. As has been mentioned bronze cannon were generally superior, lighter and were easier to cast to tight tolerances, and thus more accurate. You mention them being used on smaller armed vessels to save weight, by this period they had generally been replaced in the broadsides of sloops and brigs with larger caliber carronades of similar weight. Where they did often continue to be used were as "chasers" where accuracy was most important. Thus they were placed in the bows of sloops, brigs, and frigates, ships that would be the pursuers, and in the sterns of packets, etc. that would be the pursued.

By the era of the Revolutionary/Napoleonic Wars the majority of naval cannon were made of iron simply because it was far cheaper, and with the huge number of cannon needed quantity vs. quality became the main issue. As has been mentioned bronze cannon were generally superior, lighter and were easier to cast to tight tolerances, and thus more accurate. You mention them being used on smaller armed vessels to save weight, by this period they had generally been replaced in the broadsides of sloops and brigs with larger caliber carronades of similar weight. Where they did often continue to be used were as "chasers" where accuracy was most important. Thus they were placed in the bows of sloops, brigs, and frigates, ships that would be the pursuers, and in the sterns of packets, etc. that would be the pursued.

Great post, Lance.

Carronades were popular in Freshwater combat, since saltwater corrosion on deck cannons was reduced. A carronade has more effect against softwoods, as they splinter.

Britain controlled the supply of world tin, and had the largest copper mines, along with Sweden, in Europe. Iron processing got better, as ironmasters understood more of the chemical makeup that made iron 'Hot or cold short.'

By the era of the Revolutionary/Napoleonic Wars the majority of naval cannon were made of iron simply because it was far cheaper, and with the huge number of cannon needed quantity vs. quality became the main issue. As has been mentioned bronze cannon were generally superior, lighter and were easier to cast to tight tolerances, and thus more accurate. You mention them being used on smaller armed vessels to save weight, by this period they had generally been replaced in the broadsides of sloops and brigs with larger caliber carronades of similar weight. Where they did often continue to be used were as "chasers" where accuracy was most important. Thus they were placed in the bows of sloops, brigs, and frigates, ships that would be the pursuers, and in the sterns of packets, etc. that would be the pursued.

It should be remembered, though, that iron was lighter than bronze and the idea that iron guns were heavier than bronze as a general statement, which is made in more than one or two references is not always an accurate statement. It depends on the time period, the class of guns, and the development of metallurgy as time went on and weapons design and manufacture improved.

The problem that I've found when researching the topic of iron versus bronze as a gun metal is that guns of the same caliber are not compared in order to see the difference in weight between bronze and iron. Iron guns in the smaller calibers were generally heavier because iron was brittle and more iron was needed so that the gun tube wouldn't burst. However, iron field guns were manufactured in the United States and did quite well.

In order to actually see the difference in weight between bronze and iron naval artillery, guns of the same caliber in both metals need to be compared and contrasted.

The switch from bronze to iron for the larger calibers for naval guns became predominant by the end of the 17th century:

From Arming the Fleet by Spencer Turner:

‘The seventeenth century saw a continued swing from bronze to iron guns, an increase in the number of pieces per ship, and a shift to larger calibers. Although iron guns were still in many respects inferior to their bronze counterparts, the economic factor eventually won out. Improvements had also been made in casting iron ordnance, so that by 1626 England’s Navy Board could note that John Browne had succeeded in producing iron guns that could endure double proof and were still lighter than bronze guns.’

‘By the end of the seventeenth century, iron cannon emerged as the predominant ordnance aboard European naval vessels. In England, according to a report of 1671, only the large first-class warships were ordinarily armed with bronze cannon. One-third of the guns in second- and third-class warships were bronze. In 1677 two-thirds of the cannon in the Swedish navy were cast iron. In 1633, an observer noted in Amsterdam that less than one out of fifty Dutch ships had bronze cannon. An inventory taken in 1593 of Copenhagen’s arsenal lists 158 bronze, 344 wrought-iron, and 426 cast-iron cannon. For some, tradition died hard-in 1759 the Royal George still carried bronze guns.’

‘The first guns made specifically for the French navy were sixty cast-iron pieces ordered in 1624 and marked with an anchor showing that they were reserved for naval use. In 1661, the French navy had 760 regulation cannon ranging in size from 4 to 36 pounds. Of these, 394 were bronze and 348 iron. In 1700 the navy was armed with 8,973 guns, of which 1,177 were bronze and 7,796 were iron. By 1768 only 186 of 7,774 guns in the French navy were bronze. Notable also was the trend toward bigger guns.’-16.

Sincerely,
M

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We are not now that strength which in old days
Moved earth and heaven; that which we are we are; One equal temper of heroic hearts
Made weak by time and fate but strong in will
To strive to seek to find and not to yield.

By the era of the Revolutionary/Napoleonic Wars the majority of naval cannon were made of iron simply because it was far cheaper, and with the huge number of cannon needed quantity vs. quality became the main issue. As has been mentioned bronze cannon were generally superior, lighter and were easier to cast to tight tolerances, and thus more accurate. You mention them being used on smaller armed vessels to save weight, by this period they had generally been replaced in the broadsides of sloops and brigs with larger caliber carronades of similar weight. Where they did often continue to be used were as "chasers" where accuracy was most important. Thus they were placed in the bows of sloops, brigs, and frigates, ships that would be the pursuers, and in the sterns of packets, etc. that would be the pursued.

__________________
We are not now that strength which in old days
Moved earth and heaven; that which we are we are; One equal temper of heroic hearts
Made weak by time and fate but strong in will
To strive to seek to find and not to yield.

That was excellent. thanks
One advantage to Bronze guns was the lack of Sparking around black powder. A conservative ship chandler and captains might use bronze as long as possible. Once the bronze was in service it could be easily recycled and recast.

Interesting posts. Thanks to all.

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The trout who swims against the current gets the most oxygen..

That was excellent. thanks
One advantage to Bronze guns was the lack of Sparking around black powder. A conservative ship chandler and captains might use bronze as long as possible. Once the bronze was in service it could be easily recycled and recast.

Interesting posts. Thanks to all.

... brass/bronze doesn't rust, the cannon long outlived the ships.

Medieval cannon were made of forged iron plate, held together by hoops, the product of Blacksmiths. For example, the vast majority of Henry VIII's naval cannon were made of iron, his daughter Elizabeth I paid the big bucks and went for all brass (90 plus % rate at the time of her death). The navy was also given 1st dibs on all the fortress brass cannon in the land, which would later include Scotland & Ireland.

As Massena has pointed out, Royal Founder John Browne proved cast iron's worth in 1625, and later stated he could produce new iron cannon for the cost of melting down and recasting brass. Brass was always preferred, but given an expanding navy, larger ships, more guns and rising costs, iron was inevitable. Still, the brass went to the new ships, then the larger ships, then the more important larger ships, then the Flagships, and finally to the quarterdecks and anywhere within view of the Admiral! Then of course there was ... wrought iron.

Medieval cannon were made of forged iron plate, held together by hoops, the product of Blacksmiths. For example, the vast majority of Henry VIII's naval cannon were made of iron, his daughter Elizabeth I paid the big bucks and went for all brass (90 plus % rate at the time of her death). The navy was also given 1st dibs on all the fortress brass cannon in the land, which would later include Scotland & Ireland.

As Massena has pointed out, Royal Founder John Browne proved cast iron's worth in 1625, and later stated he could produce new iron cannon for the cost of melting down and recasting brass. Brass was always preferred, but given an expanding navy, larger ships, more guns and rising costs, iron was inevitable. Still, the brass went to the new ships, then the larger ships, then the more important larger ships, then the Flagships, and finally to the quarterdecks and anywhere within view of the Admiral! Then of course there was ... wrought iron.

The Pirate King pulls a lot of info together on how artillery designers 'thought'.

Rodman and Dalgren were the first innovators to reason through the casting process and ask"

"Why does a iron cannon have to 'look like a Bronze cannon?", and
Why do we have to cast iron in the "same old way?"

a lot of British Bronze during the Napoleonic wars was diverted into the field artillery, which forced designers to really think through how to make iron casting superior.

The manganese content of some iron ores used in Greece led to the speculations that the steel produced from that ore contains inadvertent amounts of manganese, making the Spartan steel exceptionally hard.[17] Around the beginning of the 19th century, manganese was used in steelmaking and several patents were granted. In 1816, it was noted that adding manganese to iron made it harder, without making it any more brittle. In 1837, British academic James Couper noted an association between heavy exposures to manganese in mines with a form of Parkinson's disease.[18] In 1912, manganese phosphating electrochemical conversion coatings for protecting firearms against rust and corrosion were patented in the United States, and have seen widespread use ever since.[19]

__________________
The trout who swims against the current gets the most oxygen..

By the era of the Revolutionary/Napoleonic Wars the majority of naval cannon were made of iron simply because it was far cheaper, and with the huge number of cannon needed quantity vs. quality became the main issue. As has been mentioned bronze cannon were generally superior, lighter and were easier to cast to tight tolerances, and thus more accurate. You mention them being used on smaller armed vessels to save weight, by this period they had generally been replaced in the broadsides of sloops and brigs with larger caliber carronades of similar weight. Where they did often continue to be used were as "chasers" where accuracy was most important. Thus they were placed in the bows of sloops, brigs, and frigates, ships that would be the pursuers, and in the sterns of packets, etc. that would be the pursued.

During the Anglo Swedish war, under treaty Sweden was obligated to auction off the contents of any confiscated British shipping.
However, so many British Ships crowded the Goteborg harbour that they had to put them back to sea, with a cargo of Dannemora ingots as ballast.

Though Spain cast good bronze pieces at Sevilla from 1611 at a lesser cost than those obtained from other sources the high cost of copper and tin impulsed the improvement of the casting of iron guns, wich were still regarded as unreliable

[in a previous chapter it is explained that the problem at the time was that cast iron was too brittle, the alloy was too "white" with a small proportion of carbon, with little tenacity and elasticity and not until they obtained a "grey" alloy, with more carbon and the correct mix of "white" and "grey" they could cast reliable iron cannon]

A group of Flemish founders under Juan Curcio stablished a foundry in Cantabria in 1622, using iron ore from Santander province, due to reasons of economy of transport. But despite many trials they didn't achieve good cannon.

When Curcio died in 1629 he was replaced by Jorge de La Bande, from Luxemburg, and in 1631, by mixing ore from Santander and Vizcaya had success and achieved reliable pieces, so casting of iron cannon prospered.

In 1640 another foundry was stablished and both foundries worked for over a century as a private enterprise supplying both the army and the Armada.

We can say that starting from the mid 17th century cast iron artillery became widespread in our ships.

In the beginning they started with pieces firing 9 pounds shot, with 25 calibers of length. These were reinforced pieces, bulkier than bronze guns, as uin the section of the touchhole they had a thickness of 4 diameters of the ball (4 calibers of shot). Forward of the trunnions the thickness was 3 and a half calibers, and nearly 3 at the neck. This reinforced construction was due to the brittleness of the cast iron then used, wich forced to use greater thickness to shoot with safety.

In the second half of the 17th century they already could build cast iron pieces with balls of 16 pounds and a length of 20 calibers. Metal thickness at the neck was 3 calibers. They shot with a gunpowder charge of 2/5 of the ball weight, wich was a quite efficient piece for use at sea, where long range shooting was not sought after. On one hand they were very heavy, wich was a drawback as they absorbed a lot of the displacement weight and fewer pieces could be carried, on the other hand, the larger the proportion of the weight of the carriage relative to the ball, the recoil energy was lower,[remember, recoil is conservation of linear momentum] wich was a very important consideration to avoid breaking of restraining harness or tearing of anchor hooks. [don't know the equivalent technical terms in English, so hope that is understood]

...

There's more on the powder charge varying with shots, standardization of guns and limbers dimensions expressed as calibers (and fractions of it for the rest of the equipment), description of the Spanish limber and the extreme care put into wood selection and treatment, but though very interesting is off topic, as this is about metallurgy.

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CANNON, n.
An instrument employed in the rectification of national boundaries.

Bronze cannon cost many times more than iron but until coke was introduced instead of charcoal for fuelling the furnaces there was great difficulty in producing sufficient iron of the right quality for casting. It is impossible to smelt large quantities of ore with charcoal as the weight crusheds charcoal and smothers the combustion. This revolution occurred in Shropshire in the middle of the 18th century led by Abraham Derby and others. British iron founders then led the way for some time. This was accompanied by improvements in boring techniques. Amongst the great cannon founders was the Carron company who produced the short ship smashing Carronade. French (and American) iron cannon did indeed have a greater propensity to burst until some of the changed mentioned in earlier posts were introduced mid 19th century.

Iron cannon could fire specialised loads such as grape shot and langridge which would cut up the bore of bronze cannon (the 'whiff of grapeshot' mis attributed to Napoleon is wrong - he used case shot). Both of which were used extensively in naval warfare. Iron cannon did not suffer from the distortion of the cannon mouth, caused by the rising round striking it on exit, which repeated firings could cause a bronze cannon to have an elliptical mouth which eventually would not take a round.

When the French finally mastered the techniques of firing explosive shell from cannon just after the end of the Napoleonic wars naval gunnery changed and navies went over to shell firing cannon. These were chambered with thinner walled barrels but heavier breeches (the real reason for the Dahlgren design) and these were less likely to burst as the charge was smaller (shell being lighter than cast iron cannon balls). Bronze was unsuitable material forf these in any case.